1. Field of the Invention
The present invention relates to novel furo[3,4-d]pyrimidine-2,4-dione derivatives of general formula I: ##STR1## or their intermediates of general formula II: ##STR2## as described further below. The derivatives and intermediates are useful as cardiovascular agents, such as antihypertensive or general vasodilating agents.
2. Description of the Prior Art
No examples of furopyrimidine compounds have been seen in the prior art. However, several thienopyrimidine compounds have been previously described which have a variety of biological activity. For example, Chem. Abstr. 87, 201452 describes thienopyrimidine-2,4-dione compounds of the formula ##STR3## in which R.sub.2 is methyl or phenyl and R.sub.3 is acetylenic chains with amine termini. No utility was disclosed for these compounds.
Belgian Patent No. 799238A describes thienopyrimidine-2-one compounds as CNS, uricosuric, antiviral or antiinflammatory agents. The compounds have the general formula ##STR4## Belgian Patent No. 796003 describes similar compounds having an additional substituent on the thienophene ring. The latter compounds have the same activity as the former compounds.
British Patent No. 1,057612 describes several thienopyrimidine compounds having different activities such as fungistatic, bacteriostatic, cytostatic, antiphlogistic, CNS stimulating and cardiovascular activity. Compounds of the formula ##STR5## where R.sub.1 or R.sub.2 are N-methylpiperazine are said to have good cardiovascular effects. Additional compounds include those of the following general formulas: ##STR6##
Derwent Accession Number 66-23,767/00 describes compounds of the formula ##STR7## which have coronary or peripheral vasodilator activity as well as CNS activity. In the dione compounds, R.sub.5 and R.sub.6 may be alkyl or aryl.
Chem. Abs. 104, 19606q (EP 150469) describes thienopyrimidine compounds which are antidepressants and which have the formula: ##STR8## where R may be aryl or thieno and R.sub.1 and R.sub.2 may be hydrogen, alkyl, halo or alkylene.
Finally, H. K. Gaklar et al., Indian J. Chem. Sec. B, 24B, 432 (1985) describes the preparation of thienopyrimidine-4-ones having the formula: ##STR9## No biological activity was disclosed for these compounds.
None of the thienopyrimidine compounds of the prior art discussed above contain an N-alkyl-N-arylpiperazine moiety, i.e., ##STR10## at the 3-position. Furthermore, several of the compounds are not diones and do not contain the same substituents at the 1-position of the present invention.